The present invention concerns an absorbent article, such as a diaper or an incontinence protector, comprising at least one liquid storage area with high absorption capacity and at least one wicking layer which overlaps at least a substantial part of the liquid storage area and which has greater liquid dispersion ability than the storage area, wherein the wicking layer is intended to disperse liquid collected locally in the article over the liquid storage area and wherein a liquid impermeable portion is arranged between a wicking layer and the liquid storage region.
Absorbent articles, such as diapers, pant diapers, or the like for both children and adults, are formed relatively thin in comparison with the extension in the transverse and longitudinal directions. In order to obtain sufficient capacity for accumulating emitted liquid, the absorbent material which is included in the article is spread over a large area, which area when the article is fitted on the user extends in substance from the stomach of the user via the crotch to the waist area on the back of the user.
When a user is standing or sitting, emitted urine normally ends up in the so-called xe2x80x98wetting pointxe2x80x99, which is situated in the crotch portion of the diaper, and in order to avoid local leakage near the wetting point it is important that the article is formed so that liquid is spread quickly over available absorption material. As the distance to the side edges of the article is small compared with the longitudinal extension of the article, diapers, in order to decrease the risk of lateral leakage, usually have a wicking layer to spread liquid in the longitudinal direction of the article and, at the same time, measures are taken to prevent spreading in the transverse direction outside the article.
In an attempt to prevent lateral leakage, diapers are now provided with so-called leg elastic, which holds the side edges of the article in sealing contact against the body. Leg elastic of this kind is described in, for example, U.S. Pat. No. 3,860,003. In order to further improve lateral leakage security the use of upright leakage barriers on either side of the wetting point has been U.S. Pat. No. 3,860,003. In order to further improve lateral leakage security the use of upright leakage barriers on either side of the wetting point has been suggested. Leakage barriers of this type are described in, for example, EP 0 219 326 B1.
In order to spread the liquid in the longitudinal direction of the article from the wetting point, which when the user is sitting or standing is in substance the lowest point of the article, liquid must be transported upwards against the effect of gravity. This liquid dispersion problem has occupied diaper manufacturers for several decades and a number of different types of wicking layers has been suggested in order to improve dispersion in the longitudinal direction.
U.S. Pat. No. 3,017,304, which was filed as early as 1962, describes the arrangement of a wicking layer by means of wetting of one side of an absorbent body of fluff pulp and subsequent compression of the absorbent body, which compression led to the forming of a compressed wicking layer on the wetted side of the absorbent body. In modern diapers the wicking layer is usually constituted of compressed chemical fluff pulp.
Despite great efforts, no solution has as yet emerged which gives sufficient effective liquid distribution in the longitudinal direction of the diaper in order to optimally utilise available absorption material. Diapers normally leak laterally long before all absorbent material at a distance from the wetting point has been utilised. A better utilisation of absorbent material in the article is important from the point of view of economy and is also extremely desirable for environmental reasons. If absorbent material included in diapers and the like can be better utilised, the amount of necessary absorbent material in the article could be reduced, leading to a lesser need for timber raw materials and a reduction in the amount of waste which originates from used diapers mentioned above, far from optimal. However, the problems are considerably greater in other usage situations. In particular, when the user is lying down on his or her side there is a great risk of lateral leakage. Urine emitted by the user accumulates due to the force of gravity at the lower longitudinal side edge of the article and there is a great risk of a local accumulation of liquid leading to over-saturation of locally available absorbent material, which in turn can lead to direct edge leakage or to liquid running uncontrolled along the side edge and running out where gaps occur between the article and the body of the user. Thus, when the user is lying on his or her side, leakage can occur before the main part of the absorbent material in the article has been utilised.
The aim of the present invention is to improve the liquid dispersion in absorbent articles of the type mentioned in the introduction in order to obtain a better utilisation of absorbent material included in the article compared with prior art.
In accordance with the invention, this has been achieved in that liquid-impermeable portions are arranged in the article along sections of overlapping parts of the wicking layer and the liquid storage region in order to prevent the transfer of liquid over said parts from the wicking layer to the storage region, and in that said liquid impermeable portions are placed in such a way that liquid from at least one initial accumulation place, in the form of a liquid acquisition region or in the form of a liquid acquisition region and intermediate storage regions in connection with wetting of the article is first dispersed in the wicking layer along said portions separated from the liquid storage region and thereafter is dispersed further in the liquid storage region at a distance from said accumulation place.
A problem with previously known diapers or the like has been that liquid has not been able to be spread sufficiently effectively against the force of gravity with the help of wicking layers. Liquid accumulates in the lowest situated region of the article, which is constituted by the region around the wetting with the help of wicking layers. Liquid accumulates in the lowest situated region of the article, which is constituted by the region around the wetting point when the user is standing or sitting and which is constituted by the lowest situated side portions of the diaper when the user is lying down on his/her side.
In previously known constructions the wicking and storage layers are in direct communication with each other at least in mutually overlapping portions. This means that liquid is filled into the storage layers beginning from the lowest situated point and continually upwards.
This means that liquid must be lifted higher and higher against the force of gravity as liquid is emptied from the initial accumulation point. As liquid is first emptied from the initial accumulation point out of the thickest capillaries, it becomes more and more difficult to draw the liquid from the initial accumulation point. Thus, in previously known solutions two factors act together and make the dispersion to parts of the absorbent body situated at a distance more difficult. When the liquid is to be lifted highest it is most difficult to draw liquid out of the absorbent body at the initial accumulation place.
The idea of the invention in the present application is to keep the wicking layer separated from the storage region during the extent of the first dispersion from an initial accumulation place so that liquid can be lifted a distance vertically upwards only in the wicking layer before any transfer of liquid from the wicking layer to the storage layer occurs. This means that the storage layer is not filled beginning from the vertically lowest situated parts but that liquid has first been lifted up a distance in the wicking layer. By means of this design, available absorbent material in the storage layer is utilised to a considerably greater extent. The liquid begins to be dispersed in the storage layer in a higher situated point than in previously known absorbent articles and thus reaches higher situated parts of the storage layer than has previously been possible. The idea is that the lowest situated parts of the storage layer are filled last, i.e. when it is most difficult to draw liquid out of the absorbent material in the initial accumulation place.
No-one has previously suggested using liquid-impermeable layers inside absorbent bodies in order to improve liquid distribution and achieve a better utilisation of absorbent material in the article. As the more effective liquid distribution is obtained by means of the presence of a liquid-impermeable layer between parts of overlapping portions of the wicking layer and liquid storage region, the improved effect is independent of the choice of material in the wicking layer and storage region, i.e. an improvement is always obtained by means of the presence of the liquid-impermeable layer compared to when it is absent.
It has previously been suggested in U.S. Pat. No. 4,282,874 to arrange plastic layers inside absorbent articles. However, the plastic layer in the diaper according to this publication is perforated and has the purpose of only letting liquid pass in one direction through the plastic layer, whereby the surface dryness of the article closest to the user is increased. The plastic layer in accordance with this publication covers the entire liquid storage region and therefore cannot contribute to better dispersion to portions of the liquid storage region which are situated higher during use. Furthermore, it is not arranged between the distribution layer and the storage layer, which likewise is a condition for a plastic layer arranged in an absorbent article to improve the distribution from initial accumulation places to portions situated at a distance.
WO-A-9500093 discloses an absorbent article, provided with a fluid directing component, preferably liquid impervious, which is positioned between the absorbent core and an absorbent strip, disposed immediately under the topsheet. Said absorbent strip is serving as a liquid transporting component.
No-one has previously suggested using liquid-impermeable layers inside absorbent bodies in order to improve liquid distribution and achieve a better utilisation of absorbent material in the article. As the more effective liquid distribution is obtained by means of the presence of a liquid-impermeable layer between parts of overlapping portions of the wicking layer and liquid storage region, the improved effect is independent of the choice of material in the wicking layer and storage region, i.e. an improvement is always obtained by means of the presence of the liquid-impermeable layer compared to when it is absent.
It has previously been suggested in U.S. Pat. No. 4,282,874 to arrange plastic layers inside absorbent articles. However, the plastic layer in the diaper according to this publication is perforated and has the purpose of only letting liquid pass in one direction through the plastic layer, whereby the surface dryness of the article closest to the user is increased. The plastic layer in accordance with this publication covers the entire liquid storage region and therefore cannot contribute to better dispersion to portions of the liquid storage region which are situated higher during use. Furthermore, it is not arranged between the distribution layer and the storage layer, which likewise is a condition for a plastic layer arranged in an absorbent article to improve the distribution from initial accumulation places to portions situated at a distance.
WO-A-9500093 discloses an absorbent article, provided with a fluid directing component, preferably liquid impervious, which is positioned between the absorbent core and an absorbent strip, disposed immediately under the topsheet. Said absorbent strip is serving as a liquid transporting component.
The absorbent article in accordance with WO-A-9500093 do not work satisfactory during heavy discharges of liquid from the user as the article cannot absorb large amount of liquid quickly. The liquid will instead spread over the surface and cause side leakage.
The invention will be described in more detail below in connection with some suitable embodiment examples which are shown in the attached drawings, in which FIG. 1 shows schematically in a longitudinal section the essential parts for the present invention of an absorbent article in accordance with a first embodiment.
The absorbent article in accordance with WO-A-9500093 do not work satisfactory during heavy discharges of liquid from the user as the article cannot absorb large amount of liquid quickly. The liquid will instead spread over the surface and cause side leakage.